The purpose of this program is to provide training at the postdoctoral level in the disciplines of protein chemistry, cell biology, molecular biology, developmental biology, immunology, neuroscience or genetics as they relate to the etiology and pathogenesis of blood disorders and cancer. Trainees are individuals with motivation and a scholarly background, particularly in research. Trainees will be accepted into the program for a minimum of two years, except under unusual circumstances. Most trainees will be MDs with at least 2 (and usually 3 or 4) years of training in Pediatrics or Internal Medicine, and also clinical training in Hematology and/or Oncology. Many of the MD candidates will have had previous research experience including graduation from combined MD/PhD programs. Occasional trainees are recent graduates of PhD programs who are interested in postdoctoral research related to blood diseases. We are particularly interested in attracting minority candidates. It is expected that all trainees will acquire PhD-equivalent research experience and that many will acquire additional training equivalent to a PhD postdoctoral experience. The program of training will take place in our own laboratories and in laboratories throughout the Boston biomedical community under the guidance of outstanding and experienced preceptors. Many of these laboratories are in a hospital environment and many of the preceptors and trainees will have clinical training. This encourages correlation of basic laboratory studies with current health problems, especially related to blood disorders. Training will also include participation in didactic courses, attendance at formal lectures and seminars, involvement with relevant research literature, practice in oral presentation, and frequent informal conferences and evaluations of the trainees' ongoing research.